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Monday, November 24, 2014

Turkey Virtue

Our Friendsgiving Spread this year included turkey cooked sous vide and skin cooked ala plancha.

This week is the American Thanksgiving celebration, a time of traditional foods, centered around eating turkey. It isn't some simple obsession, the American tradition requires serving a roasted bird whole to be carved at the table as a highlight. Cooking this unwieldy beast in this manner is a biophysical challenge that drives people to ornate lengths, but perhaps the shared adversity serves to bond families and tribes together, albeit in ritual.

Noting the unusually high demand for this meat in this season, Maryn McKenna penned an article on Wired urging people to buy "antibiotic-free turkey" to "slow down drug resistance in health care" (a more accurate phrase than stopping drug resistance). Basically, it highlights the Sharing Antimicrobial Reports for Pediatric Stewardship (SHARPS) pledge to encourage purchasing "turkey raised without routine use of antibiotics"). Notice, however, how the two phrases are so readily interchanged. I've written before how there really is no such thing as "antibiotic-free" meat. That phrase is based on the conceit that antibiotics are only synthetic products added by humans, when in fact wherever microbes interact with each other, they produce antibiotics - some of which we may exploit one day for human use. That's not even considering the fact that the antibiotic classes used in farms overlap in a very minor manner with the clinically relevant types.

What puzzles me, though: why target turkeys? Are turkeys a notable reservoir for incubating clinical antibiotic resistance? McKenna's article links out to a 2013 Consumer Reports article that points to conventionally grown turkey as a "persistent source of antibiotic resistant bacteria". For its claims of testing, this article did not adhere to good scientific reporting: it did not completely document the methodology for the sample collection and testing, and lacked controls and proper replication. Most any microbiologist will note in the sloppy nomenclature that the testing design was amateurish. Put into context - finding antibiotic resistant bacteria is actually quite easy, as it predates the development of modern antibiotics. From what I can tell, the writers conflated detection of bacteria post culture with the emergence of antibiotic resistance, and that just serves to confuse the reader. In fact, even birds "raised without antibiotics" yielded significantly antibiotic resistant bacteria — unsurprising, given the survey design.

The SHARPS Tumblr post linked from the article writes: "It has been shown in study after study that use of low-level antibiotics leads to the emergence of resistant bacteria." Both of these studies were done in cattle, and in the second study, the type of diet fed to the animals correlated more strongly to the emergence of antibiotic resistance traits than the use of antibiotics.

An investigation last year (about the same time this sloppy Consumer Report article was published) by NPR's The Salt couldn't find specific data on antibiotic use in raising turkey as the industry doesn't track this information.

So, I remain unconvinced how pledging to buy birds that are specifically labelled "antibiotic-free" or "raised without routine antibiotic use" is going to help impede the evolution of clinically relevant antibiotic resistance traits. But what this will do is create a virtuous halo around producers that label their turkeys in this manner - but how do you know what was turkey labeled as "raised without routine antibiotic use" was indeed raised so? Is there an enforcing body? Not to start a conspiracy theory but where there's a profit motive, fraud becomes tempting. And instead of raising awareness of this complicated topic (which requires a good understanding of evolutionary theory), people will compartmentalize it into virtuous fads.

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